#
with open('a.txt', mode='r') as fr1:
    a1 = fr1.readlines()
    print(a1)
with open('b.txt', mode='r') as fr2:
    a2 = fr2.readlines()
    print(a2)
s1 = set(a1)
s2 = set(a2)
s3 = s1.difference(s2)
a3 = list(s3)
print(a3)
with open('c.txt', mode='w') as fc:
    fc.writelines(a3)

